I attempted to be a Fi user. I was a Google Voice number, but apparently some small % of Google Voice numbers could not be ported into Fi at all. After a couple escalations the rep was very sorry but said their system was not able to handle my account unless I was willing to give up my Google Voice number. They suggested I create an alternate google account just for Fi, although Fi and Google Voice cannot front one another, so I end up with a separate phone number that nobody would know.